Anorectal dysfunction encompasses a whole range of heterogeneous disorders, which are oftentimes difficult to fully evaluate and treat optimally by clinical examination. With this in mind, we have come up with this video entitled, Multicompartmental Ultrasound Approach to Anorectal Dysfunction. Here, we will be demonstrating how ultrasound can be useful in the evaluation of both defecatory dysfunction and anal incontinence, with emphasis on the common causes of obstructed defecation, which is mainly anatomic, and sphincter injury, which may lead to fecal and or flatule incontinence. Briefly going over the anatomy of the female pelvis, it can be divided into the anterior, posterior, and lateral compartments. The term pelvic floor pertains to all the structures supporting the pelvic cavity, which include the levator ani muscles, as well as the connective tissue attachments to the pelvic sidewall. The role of the levator ani muscles and pelvic support cannot be overemphasized. These consist of the ilic oxygous, the pubic oxygous, and the puborectalis muscle. Once the pelvic musculature becomes damaged and no longer holds organs in place, the ligaments are subjected to excessive forces, and prolapse occurs. The three structures that are responsible for fecal continence include the internal anal sphincter, the external anal sphincter, and the puborectalis muscle. So what is the multi-compartmental approach? By using a combination of transducers, all compartments of the pelvic floor can be examined with detailed resolution. It includes detailed anatomic with dynamic functional examinations and can be performed in a few minutes when experienced physician. In patients with defecation symptoms like straining, incomplete bowel emptying, and need to splint with bowel movements, imaging of the pelvic floor is done using a combination of the following three steps. The 8802 probe is used for transperineal or translateral scanning. The 8848, 8838, and 2052 are all endocavitary transducers used for endovaginal or endoanal scanning. Dynamic 2D scanning and 3D volume acquisition can be done. With a patient at rest, positioned in dorsal lithotomy with hips flexed and slightly abducted, the 8802 transducer is placed in such manner. In the sagittal view, causes of obstructed defecation such as rectoceles, enteroceles, sigmoidoceles, and dysenergy may be seen. At rest, the starting two-dimensional view includes the following from anterior to posterior, the pubic bone, bladder and urethra, vagina, rectum, and levator plate. A good quality image contains both the pubic bone and the levator plate, and measuring the distance from the symphysis pubis to the levator plate gives the anterior-posterior diameter of the levator hiatus, which is an important parameter to evaluate. Dynamic imaging is obtained by asking the patient to perform Valsalva. Here we would be able to visualize the movement of the anterior, apical, and posterior compartments. A true rectocele is herniation of the rectal wall through a defect in the posterior rectovaginal septum. In this video, note the bulge into the posterior vagina where the arrow is pointing. This is a small rectocele. Presence of hyperechoic stool is typical of a rectocele. Here is a more obvious rectocele. Its extent can be measured as the maximal depth of protrusion beyond the inferior symphysial margin. A descent of greater than 10 millimeters is considered diagnostic. Enterocele is hernia of the most inferior point of the abdominal cavity into the vagina or pouch of doglass. It is ultrasonographically visualized as downward displacement of abdominal contents into the vagina, ventral to the rectal ampulla, and anal canal. Here is another enterocele. Small bowel may be identifiable due to its peristalsis. Again, the extent of an enterocele is measured against inferior margin of the symphysis pubis. Here is a sigmoidoscele with hyperechoic stool. Differentiating it from enterocele is important for surgical planning. If not recognized, redundant sigmoid colon will continue to cause defecatory dysfunction even after repair of the prolapse. Using the 8848 for endovaginal posterior compartment imaging, the probe is generally advanced until the perineal body is to the right of the screen. Slight anterior pressure is desired when patient is prompted to cough or valsalva. The anal canal and the levator plate come to view. By asking the patient to squeeze or valsalva, a rectocele may be visualized. Intussusception occurs when the rectal wall telescopes into the rectal lumen and can involve the rectal mucosa as seen here, or full thickness of the rectal wall. It can be classified as intrarectal, intraanal, or external if it forms a complete rectal prolapse. Pelvic floor dyssynergy is characterized by a lack of normal relaxation of the puborectalis muscle during defecation. This can be a difficult condition to verify through clinical examination. During valsalva, it can be documented by ultrasound because the anorectal angle becomes narrower, the levator hiatus is shortened, and the puborectalis muscle thickens. Using the 2052 probe, 360 endovascular scanning is started at the level of the vesicourethral junction. Pressing the 3D button will obtain a series of axial images which will be packaged as a 3D volume. The pubic symphysis and urethra are anterior, the levator ani lateral, and the anus posterior. Evaluation of the levator ani muscles and measurement of levator hiatal dimensions can then be done. Note the area of levator hiatus bounded by the inferior pubic rami and levator ani muscles. Knowing the measurement of the anorectal angle and the position of the levator plate are also important. 3D endoanal ultrasound is the gold standard for the morphological assessment of the anal canal. It is the last step in the multi-compartmental approach and may be performed with the 8838 or 2052 probe. Its most relevant utility applies in the detection of localized external and internal anal sphincter defects. Endoanal imaging can be divided into three levels of assessment in the axial plane. In the upper level, the sling of the puborectalis, deep part of the external anal sphincter, and the complete ring of the internal anal sphincter can be appreciated. The middle level shows the superficial part of the external and internal anal sphincters as complete rings, the conjoined longitudinal layer, and the transverse perineal muscles, while the lower level shows the subcutaneous part of the external anal sphincter. Sphincter lesions include a whole range of defects which may vary from scarring, thinning, thickening, or atrophy. Note the prominent appearance of the internal anal sphincter on the left and the defect from 11 to 12 o'clock up to 4 o'clock position. On the other hand, an external anal sphincter defect is a break in the circumferential integrity of the mixed hypoechoic band. Note the hypoechoic external anal sphincter defect on the right. In conclusion, ultrasound visualization of the pelvic floor requires a multi-compartmental approach. Knowledge of pelvic anatomy and functionality of different probes is essential for acquisition of meaningful images. Ultrasound can reliably detect whether the patient with defecatory symptoms has anatomical or functional abnormalities. This will allow us to improve current therapeutic options and develop entirely new approaches which target underlying pathology. Thank you.

ultrasound

anorectal dysfunction

defecatory dysfunction

obstructed defecation

anal incontinence